You definitely want to look into "E6", there's a couple of PDF's out there from its creator that explain it very well. I *think* the latest version is 0.4.1, but I'm not sure.
The basic concept is that 6th level PC's are already practically gods,
compared to the average peasant anyway. But not so god-like that a large group of well-trained guards still can't kill you. He stopped at 6th level partly because 4th-level spells start to overpower the game. Once you hit (or start at) 6th level, you get a new feat every 5000 XP. It uses all the features of the underlying system (3.5 or Pathfinder), with the exception of some new above-6th-level feats.
But on the other hand, the way Pathfinder works things, you get some nice perks at 8th level, which makes it a reasonable place to stop, but now you have to deal with those pesky 4th-level spells. There's good discussions of that
here and
here.
I've looked at E6 in some detail, it seems well thought-out and was extensively play-tested by its creator's group. I've never played it, but many people seem to like it.